From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753662AbcBORdu (ORCPT ); Mon, 15 Feb 2016 12:33:50 -0500 Received: from mail-wm0-f68.google.com ([74.125.82.68]:33479 "EHLO mail-wm0-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753514AbcBORds (ORCPT ); Mon, 15 Feb 2016 12:33:48 -0500 Date: Mon, 15 Feb 2016 18:33:46 +0100 From: Michal Hocko To: Tejun Heo Cc: Mike Galbraith , LKML Subject: Re: [PATCH wq/for-4.5-fixes] workqueue: handle NUMA_NO_NODE for unbound pool_workqueue lookup Message-ID: <20160215173346.GA26207@dhcp22.suse.cz> References: <1454424264.11183.46.camel@gmail.com> <20160203185425.GK14091@mtj.duckdns.org> <20160210155503.GE3741@mtj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160210155503.GE3741@mtj.duckdns.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 10-02-16 10:55:03, Tejun Heo wrote: [...] > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -570,6 +570,16 @@ static struct pool_workqueue *unbound_pwq_by_node(struct workqueue_struct *wq, > int node) > { > assert_rcu_or_wq_mutex_or_pool_mutex(wq); > + > + /* > + * XXX: @node can be NUMA_NO_NODE if CPU goes offline while a > + * delayed item is pending. The plan is to keep CPU -> NODE > + * mapping valid and stable across CPU on/offlines. Once that > + * happens, this workaround can be removed. I am not sure this is completely true with the code as is currently. Don't wee also need to use cpu_to_mem to handle memoryless CPUs? > + */ > + if (unlikely(node == NUMA_NO_NODE)) > + return wq->dfl_pwq; > + > return rcu_dereference_raw(wq->numa_pwq_tbl[node]); > } diff --git a/kernel/workqueue.c b/kernel/workqueue.c index c579dbab2e36..4785b895b9b5 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1325,7 +1325,7 @@ static void __queue_work(int cpu, struct workqueue_struct *wq, if (!(wq->flags & WQ_UNBOUND)) pwq = per_cpu_ptr(wq->cpu_pwqs, cpu); else - pwq = unbound_pwq_by_node(wq, cpu_to_node(cpu)); + pwq = unbound_pwq_by_node(wq, cpu_to_mem(cpu)); /* * If @work was previously on a different pool, it might still be -- Michal Hocko SUSE Labs